Cache gfx::RenderText instances in views::Label.

ui/gfx/render_text.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_RENDER_TEXT_H_
 #define UI_GFX_RENDER_TEXT_H_
 
 #include <algorithm>
 #include <cstring>
 #include <string>
@@ skipping 175 matching lines @@
 // complex scripts, and bi-directional text. Implementations provide mechanisms
 // for rendering and translation between logical and visual data.
 class GFX_EXPORT RenderText {
  public:
   virtual ~RenderText();
 
   // Creates a platform-specific or cross-platform RenderText instance.
   static RenderText* CreateInstance();
   static RenderText* CreateInstanceForEditing();
 
+  // Returns true if the current RenderText subclass supports multilines.
+  static bool MultilineSupported();
+
   // Creates another instance of the same concrete class.
   virtual scoped_ptr<RenderText> CreateInstanceOfSameType() const = 0;
 
   const base::string16& text() const { return text_; }
   void SetText(const base::string16& text);
 
   HorizontalAlignment horizontal_alignment() const {
     return horizontal_alignment_;
   }
   void SetHorizontalAlignment(HorizontalAlignment alignment);
@@ skipping 205 matching lines @@
   // supplied index is already at the boundary of the string.
   size_t IndexOfAdjacentGrapheme(size_t index,
                                  LogicalCursorDirection direction);
 
   // Return a SelectionModel with the cursor at the current selection's start.
   // The returned value represents a cursor/caret position without a selection.
   SelectionModel GetSelectionModelForSelectionStart();
 
   // Sets shadows to drawn with text.
   void set_shadows(const ShadowValues& shadows) { shadows_ = shadows; }
-  const ShadowValues& shadows() { return shadows_; }
+  const ShadowValues& shadows() const { return shadows_; }
 
   typedef std::pair<Font, Range> FontSpan;
   // For testing purposes, returns which fonts were chosen for which parts of
   // the text by returning a vector of Font and Range pairs, where each range
   // specifies the character range for which the corresponding font has been
   // chosen.
   virtual std::vector<FontSpan> GetFontSpansForTesting() = 0;
 
   // Gets the horizontal bounds (relative to the left of the text, not the view)
   // of the glyph starting at |index|. If the glyph is RTL then the returned
@@ skipping 295 matching lines @@
   // Lines computed by EnsureLayout. These should be invalidated with
   // ResetLayout and on |display_rect_| changes.
   std::vector<internal::Line> lines_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderText);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RENDER_TEXT_H_